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Genetic parameters: assessing several traits

A study completed by the University of Czech Republic estimated the genetic parameters for fertility traits and linear type traits in Holstein cows. Phenotypic data for 12 linear type traits, measured in first lactation, and three fertility traits measured in both first and second lactation were collected from 59,467 cows; for the trait of mobility 53,436 records were available.

Findings from the collected data, published in the October 2011 issue of the Journal of Dairy Science, include:

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Heritability estimates for reproduction traits were low, ranging from 0.02 to 0.04 and heritability estimates for linear traits ranged from 0.02 for mobility to 0.39 for stature.

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Estimated genetic correlation between fertility traits and linear type traits were generally neutral or positive. On the other hand, genetic correlations between body condition score, calving to first service and days open were mostly negative, with a large negative correlation between body condition score and days open from calving to first service in first and second lactation.

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Genetic correlations were the greatest between mobility and calving to first service in both first and second lactation,

After analysis of the results, researchers have concluded cows that are genetically extreme for angularity, stature and body depth tend to perform poorly for fertility traits. Likewise, cows that are genetically prone for low body condition score or high mobility are generally inferior in fertility.